It was evaluated at Porton Down.

A new coronavirus antibody test has been found to be 100% accurate, public health leaders have said.

Public Health England (PHE) said that last week the scientific experts at its Porton Down facility had carried out an independent evaluation of a new antibody blood test developed by a Swiss pharmaceutical company.

The examination found that Roche’s serology test was “highly specific” and had an accuracy of 100%.

The findings have been hailed as a “very positive development” in combating the coroanvirus outbreak.

The test is designed to help determine if a patient has been exposed to the virus that causes Covid-19 and whether they have developed antibodies against it.

This is a very positive development because such a highly specific antibody test is a very reliable marker of past infectionProfessor John Newton

The detection of these antibodies could help to indicate if a person has gained immunity against the virus.

Professor John Newton, national coordinator of the UK Coronavirus Testing Programme, said: “We were confident that good quality antibody tests would become available when they were needed.

“Last week, scientific experts at PHE Porton Down carried out an independent evaluation of the new Roche Sars-CoV-2 serology assay in record time, concluding that it is a highly specific assay with specificity of 100%.

“This is a very positive development because such a highly specific antibody test is a very reliable marker of past infection.

“This in turn may indicate some immunity to future infection although the extent to which the presence of anti-bodies indicates immunity remains unclear.”

The Department of Health and Social Care (DHSC) said it was delighted that devices were progressing through validation and was working on plans to roll out antibody testing.

It added that an announcement will be made “in due course”.

A spokeswoman said: “Antibody testing is an important part of our strategy to counter the spread of Covid-19 and to help us understand who has had the disease.

“In addition to the recent huge expansion of the UK’s swab-based coronavirus testing capacity, we are exploring the use of antibody testing across the NHS and ultimately the wider public.

“We are delighted that devices are progressing through validation, and are actively working on our plans for rolling out antibody testing and will make announcements in due course.”

Health Secretary Matt Hancock last week said the UK was in talks with Roche about a “very large-scale roll-out” of coronavirus antibody testing.

Speaking at the daily Downing Street press briefing on May 4, Mr Hancock said: “Today, Roche, the Swiss global diagnostics company, made a very positive announcement about progress with their antibody test and we’re in discussions with them about a very large-scale roll-out of antibody testing, as well as with some others who may be able to bring this forward.”

But Mr Hancock acknowledged that there had been problems with antibody testing, having previously said the UK would order 17.5 million home testing kits only to find they did not work.

“There has been false hope before in antibody testing and so we’ll make announcements when we’re absolutely ready,” he said.